1 . Technical Field
The present disclosure relates to a countermeasure method for protecting sensitive data processed in an electronic component, against attacks aiming to discover these data. It also relates to a portable device with a microcircuit such as a chipcard, implementing the method.
Sensitive data can be, for example, encryption or decryption keys. More generally, it may be cryptographic data used or developed during cryptographic calculations, such as intermediary data of such calculations, and identifiers that are kept secret.
2. Description of the Related Art
Microcircuit devices manipulating sensitive data are sometimes the objects of attacks aiming to determine these data. Among the known types of attacks, Simple Power Analysis SPA or Differential Power Analysis DPA type attacks comprise measuring input and output currents and voltages of the microcircuit during the execution of a program by the microcircuit, with the goal of deducing the protected data used or processed by the microcircuit. With this same goal, attacks of the Electromagnetic Analysis EMA type are based on the analysis of the electromagnetic radiation emitted by the microcircuit. For example, the switching of logic gates causes electrical current consumption and electromagnetic radiation of the circuit. By detecting these variations, it may be possible to determine the data on input or output of logic gates.
Also known are fault injection attacks that consist of introducing perturbations in the microcircuit while it is executing sensitive algorithms such as cryptographic algorithms, or with the aim of launching a downloading routine of the data onto a port, which it then stores. Such a disturbance may be done by applying one or more brief lightings or voltage peaks on one of the contacts of the microcircuit.